A few tips on checking and preparing an M1903 of unknown provenance for shooting;
-remove the barrelled action from the stock and check the receiver for cracks (surprisingly I once found a Rem M1903 with a cracked receiver ring). This can be done by either immersing the receiver in a quick evaporating solvent, which will cause the solvent to show up in a crack, or by holding the stripped receiver/barrel by the muzzle end and whacking the receiver with something like a wooden hammer handle. An uncracked receiver will give a ringing sound when struck. A cracked receiver will give a dull thud.
- verify headspace with a set of headspace gauges or, as a minimum, with a .30-06 "field" headspace gauge. The chamber should be clean and dry before checking headspace.
- scrub the bore well with a bronze brush to remove excess crud and corrosion. JB paste is a useful follow-up to brushing a neglected bore.
- verify that the rear face of the third bolt safety lug does not make hard contact with the corresponding surface of the receiver. If there is hard contact here the safety lug will act as a recoil lug and can relieve contact between the rear of the 2 bolt lugs and their seats in the receiver, a dangerous situation.
-if possible gauge the bore for wear/erosion. In the absence of a muzzle gauge a reversed round can be inserted in the muzzle. If the bullet enters the muzzle to a point where the bullet cannelure or case mouth makes contact with the muzzle, the muzzle is excessively worn and will not shoot well. The muzzle crown should also be smooth and free of gouges. A worn bore can still shoot reasonably well if the crown is in good shape. I once had an M1903 which gauged 307 on the GI throat gauge, versus a reject reading of 308, and a muzzle with a .303 reading on the gauge. After the crown was cleaned up it still produced 3" groups @ 100 yds.
-the barrel should be free of contact with the stock, except at the forend tip where 5-7 lbs pressure is necessary to lift the barrel free of contact with the stock. The top of the barrel must be free of contact with the metal on the inner surface of the upper band.
- there must be clearance between the rear face of the upper tang of the receiver and the corresponding inletting of the stock. If there is contact here the tang will act as a recoil lug and split/crack the stock. This can be remedied by installing a "pop can shim" between the rear face of the recoil lug and the seat for the recoil lug in the stock.
- the metal bushing/sleeve for the rear guard screw must be installed in the stock.
- the rear sight must be tight. A worn windage screw will need replacement. The fit of the movable sight base can also be a problem. The front sight must also be tight in the front sight stud of the barrel. The screw on the rear sight slide must also fit tightly. The best shooting is done using the "peep sight" in the rear sight slide.
- the front guard screw must be "gorilla tight". The rear guard screw must also be tight, but not as tight as the front one. Before tightening the guard screws bump the buttplate on a 2x4 or wood surface to seat the recoil lug in the stock and then tighten the front screw followed by the rear one. Bring the front screw to full tightness before the rear one.